A series of problems forced LHC shutdown (CERN/LHC)

Helium Leak Forces LHC Shutdown for at Least Two Months

Article Updated: 24 Dec , 2015

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It’s this sort of news I really did not want to wake up to. At 0927 GMT Friday morning, a fault known as a “quench” resulted in the leakage of a tonne of helium coolant causing 100 of the LHC superconducting magnets to heat up 100°C. The fire services had to be called and it was some time before engineers could access the tunnels to assess the damage. It was worse than they were expecting. Although no one was hurt and there was no danger to the public, the once-supercooled magnets were one hundred times warmer than they should be and optimal vacuum conditions had been lost. To perform repairs, the rest of the damaged sector will need to be warmed up and then slowly cooled down again, resulting in a shutdown of LHC operations for at least two months

The leak occurred between the Alice and CMS detectors (sectors 3-4) after repairs to the faulty 30-tonne transformer were being finalized and the systems were being powered up to begin a new series of commissioning tests. According to the LHC logbooks, temperatures rose by 100°C and the vacuum required within the equipment for particle circulation to be possible was lost. Engineers had to wait for oxygen levels to return to normal within the tunnels before they could investigate the “meltdown.”

Although last week’s fault with the transformer caused frustration, setting LHC experiments back by a few days, scientists were optimistic the incident would have minimal effect on the first scheduled particle collisions in October. Friday’s quench, however, is a serious incident, knocking the largest experiment mankind has ever attempted offline for at least two months. Although this is sad news, many scientists are keeping a positive attitude:

This kind of incident was always a possibility with such a unique and demanding project, that’s why we were so tense on the 10th [of September]. Having seen those tantalising first signs of beam in our detectors, everyone is raring to go. So it’s really disappointing, and hard for us to keep in perspective right now. But a delay like this in a 20-year project isn’t an utter disaster and I’m sure the team at Cern will fix it, and make it more robust as they go.” – Prof Jonathan Butterworth of University College London, the UK head of the Atlas detector.

So what happened? The basic operating conditions for the LHC depend on very low temperatures and a very high vacuum state. It would appear both key conditions were lost as engineers tested the electrics of the LHC in the run-up to full commissioning. There was a faulty connection between two of the superconducting magnets, so when the system was switched on, the high current melted the connection, causing the helium leak. The loss of supercooled helium caused a rapid release of stored energy (an event known as a quench), heating the magnets and destabilizing the vacuum conditions.

After such a smooth start to the first proton circulation on September 10th, these setbacks may come as a surprise. However, probing the frontier of physics rarely happens without a few hiccups along the way, so let’s hope this incident will be the last and we can once again look forward to the first particle collisions toward the end of the year…

Sources: BBC, Telegraph


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voyager
Guest
voyager
September 20, 2008 2:27 PM

sad hope they’ll fix this soon

Tammy Plotner
Member
September 20, 2008 1:38 PM

Ian?

You should check this out…

PMF71
Member
PMF71
September 20, 2008 3:39 PM

LOL @ Tammy, that was good one, LOL

marcellus
Guest
marcellus
September 20, 2008 10:47 PM

Black holes, the 2012 doomsday prediction, the annual euchre tournament at the Cydonian complex on Mars…..

Where will it all end?

Darnell Clayton
Member
September 20, 2008 5:16 PM

@ Tammy: LOL! I should have shown that to all of the “black hole” phobics before news of the shutdown occurred.

@ Ian: I’m guessing they will encounter another hiccup, and we will see this thing become operational in January, right when the next President is elected.

And then right after that, a black hole will form. wink

Tammy Plotner
Member
September 20, 2008 5:57 PM

heheheee… wicked, aren’t i? wink

mcenhillk
Member
mcenhillk
September 20, 2008 6:43 PM
A quench occurs when a portion of the superconducting wire goes normal. That normal section of wire suddenly goes from no resistance to nano-ohms of resistance. It doesn’t sound like much but when there are hundreds of amps running through the wire and the temperature is single digit Kelvin, it doesn’t take many watts to cause the surrounding wire to go normal. A chain reaction loops completely around the magnet till the entire coil is normal. The remaining energy boils off the remaining liquid helium. Once the helium is gone, the rest of the energy raises the temperature of the magnet. I worked on a superconducting medical cyclotron in the ’90s. The cryostat held 80l of liquid helium.… Read more »
Don Alexander
Member
Don Alexander
September 20, 2008 9:52 PM

NO! NO! NO! NO! NO! NO! NO! NO! NO! NO! NO!

I am in denial… sad

We wait years and years, and then they FINALLY have it up and starting to run, and it breaks…

Well, now we can create some anti-conspiracy theorist theories, as in:

The I-fear-the-black-hole-will-eat-me-ers lainched a terrorist attack on the LHC!!!

@mcenhillk: Great post, very informative!

I do have a question/observation. If you have 80l of LHe, each l gives you 800l of gas, that’s 64,000l of gas or 64 cubic meters or a cube of 4 meters side length.

I half a second?? Sounds pretty much like a small explosion!! Not to mention the fact that the oxygen would be gone…

darko
Guest
darko
September 20, 2008 10:07 PM

now wht?

black hole!suck’em brain!

~_~

littlerobin
Guest
littlerobin
September 20, 2008 10:38 PM
question: I have a more practical one. If the LHC does indeed produce a mini black hole, could we then prove that Hawking radiation exists? If so, what would be the consequences? answer: It is possible. The eventual end of every black hole could well be the same evaporation that will be seen with the quantum effects that should be the result of these mini-black-holes as they disappear. The possible problems in detecting them, however, are enormous. Not only is the “black hole” only supposed to last for about 0,00000000000000000000000001 seconds, the measurement process is still in the theoretical stage. There’s also the possibility that the Hadron collision might not produce a black hole. At this point that… Read more »
Unbeliever
Guest
Unbeliever
September 20, 2008 10:47 PM

can you say “sabotage” ?

mcenhillk
Member
mcenhillk
September 20, 2008 11:24 PM
@Don Alexander: I think the cryostat had a total internal volume of 150l. It had something to do with the fact that we flipped the cyclotron 360 degrees around the patient. With that volume and 64,000l of gas, things get “sporty”. The nice thing about helium is it’s compressibility. Instead of a detonation and it’s associated shock wave, we got a quick pressurization. The burst plate popped at 5psi so it blew very quickly. This opened up a 2″ vent to the outside of the building. The only thing that could hurt those of us working on system is holding on to that vent during a quench. Nothing give you frost bite faster than holding on to a… Read more »
alandee
Guest
alandee
September 21, 2008 3:57 AM

I’m guessing your all saying all of these things with high squeaky voices !

.. that is helium right ?

/ignorance ..

vino
Member
vino
September 21, 2008 4:16 AM

@Tammy: thanks for a wonderful video….

Vanamonde
Guest
Vanamonde
September 21, 2008 1:37 PM

“Saved the drama for your mamma” This is a new machine – never has their been any cyrogenic device on this scale. Stuff happens. Stuff will happens again. I’m disappointed but these thing teach and I am sure CERN will overcome this setbeck. Research the early days of space flight and the ole Vanguard project! Or the many attempts to land a craft on the Moon (the Ranger program). This is just was complex…if not more.

Dave
Guest
Dave
September 21, 2008 3:39 PM

I think maybe the temperature went up BY 100 C rather than TO 100 C.

Richard
Guest
Richard
September 21, 2008 5:25 PM

Hope they can get it working soon, ready to see what it will do.

Gaelynsgirl
Guest
Gaelynsgirl
September 21, 2008 6:15 PM

Kind of reminds me of the early days of Hubble! Once the glitches are ironed out, I’m sure the LHC will deliver up a Higgs boson with as much excitement as (or more than) the ‘resolved’ Hubble problems have provided for observational astronomers. Hang in there you particle physicists. Your time will come!

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